1. Field of the Invention
The present invention relates to a passively activated safety shield for a needle, such as the needle for an IV infusion set or a blood collection set.
2. Description of the Related Art
A blood collection set or IV infusion set includes a needle cannula having a proximal end, a pointed distal end and a lumen extending therebetween. The proximal end of the needle cannula is securely mounted in a plastic hub with a central passage that communicates with the lumen through the needle cannula. A thin flexible thermoplastic tube is connected to the hub and communicates with the lumen of the needle cannula. The end of the plastic tube remote from the needle cannula may include a fixture for connecting the needle cannula to a blood collection tube or some other receptacle. The specific construction of the fixture will depend upon the characteristics of the receptacle to which the fixture will be connected.
Most needle assemblies include a safety shield that can be moved into shielding engagement with a used needle cannula without risking an accidental needle stick.
Some needle shields are referred to as tip guards, and include a small rigid guard that can be telescoped along the length of a needle cannula. The prior art tip guard may include some form of tether for limiting the travel of the tip guard to the length of the needle cannula. Additionally, the prior art tip guard typically includes structure that lockingly engages over the tip of the used needle cannula to prevent a re-exposure. The structure for preventing re-exposure may include a metallic spring clip or a transverse wall integrally formed with one end of the tip guard.
However, most shields for used needle cannulas require direct manual activation by the medical practitioner.
Therefore, there is a need to provide a passively shieldable needle assembly that will achieve secure shielding of a used needle cannula automatically upon removal of the needle cannula from the patient.
The present invention is a passively shieldable needle set. The needle set includes a needle cannula having a proximal end, a pointed distal end and a lumen extending therebetween. The needle set further comprises a hub having a proximal end, a distal end and a passage extending between the ends. The proximal end of the needle cannula is securely mounted in the passage of the hub. A flexible tube may be mounted to the proximal end of the hub, such that the passage through the tube communicates with the lumen of the needle cannula. A fixture may be mounted to the end of the tube remote from the hub. The fixture enables the needle cannula and the tube to be placed in communication with an appropriate receptacle, such as a blood collection tube.
The needle set further includes a passive shield assembly. The shield assembly includes an end cap having a blocking surface that is slidably telescoped on the needle cannula for movement from a proximal position where the end cap is substantially adjacent the hub to a distal position where the blocking surface of the end cap surrounds the pointed distal end of the needle cannula. Additionally, the end cap may be configured to prevent proximal movement after the blocking surface of the end cap has advanced sufficiently in a distal direction to protectively enclose the distal tip of the needle cannula.
The end cap may comprise a housing and a protective clip, each of which is formed from a material that is sufficiently hard and rigid to prevent piercing by the distal tip of the needle cannula. The housing may be formed from a thermoplastic material, and the clip may be formed from a metallic material. The clip is configured to be biased against the needle cannula as the end cap moves from its proximal position toward the distal position. However, the clip is further configured to move over the tip of the needle cannula when the end cap is in its distal position.
The passive shield assembly further includes a pair of resiliently deflectable leaves. The leaves have proximal ends that are connected to opposite respective sides of the hub. The leaves further have distal ends connected to opposite respective sides of the tip guard. A portion of each leaf between the respective ends is resiliently collapsible onto itself and into close overlying relationship to the needle hub. Thus, the collapsed leaves can be manually gripped by the medical practitioner to manipulate the needle assembly prior to and during veinipuncture. However, a release of forces on the collapsed leaves enables the leaves to resiliently move toward an undeflected condition in which the leaves extend substantially linearly and parallel to one another on opposed sides of the needle cannula. This resilient unfolding of the leaves transports the tip guard distally along the needle cannula. The leaves have lengths sufficient to enable the tip guard to move into shielding engagement with the tip of the needle cannula, without moving distally beyond the needle cannula.
The needle set further includes a packaging cover having an open proximal end, a distal end, and a generally tubular sidewall extending therebetween. Portions of the sidewall of the packaging cover adjacent the open proximal end are configured to be frictionally mounted over the hub and partially over the collapsed leaves. Thus, the packaging cover functions to hold the leaves in their collapsed condition. The sidewall of the packaging cover is sufficiently long to cover the needle cannula when the proximal end of the packaging cover is mounted to the hub.
A medical practitioner employs the needle set of the subject invention by gripping the collapsed leaves of the shield assembly between a thumb and forefinger at a location proximally of the packaging cover. The packaging cover then is removed, and the tip of the needle cannula is inserted into a blood vessel of a patient. Upon completion of the insertion, the medical practitioner releases the grip on the collapsed leaves, and the leaves begin to unfold due to their inherent resiliency. The unfolding of the leaves causes the tip guard to move distally along the needle cannula. The distal movement of the tip guard will terminate when the tip guard contacts the skin of the patient. After completion of the medical procedure, the practitioner grabs the needle hub or tubing with a thumb and forefinger and pulls the needle cannula from the patient. This relative proximal movement of the needle cannula will permit the leaves to unfold further, thereby moving the tip guard into surrounding relationship to the tip of the needle cannula. The clip or other such structure within the tip guard will prevent a re-exposure of the used needle cannula.
Although the shield assembly is triggered by the medical practitioner, shielding is entirely passive and automatic after the triggering. The triggering action is the release of the collapsed leaves by the medical practitioner. This release can occur after the needle cannula has been placed properly in a blood vessel. Alternatively, this triggering can occur if the needle set is inadvertently dropped. The elapsed time for this shielding will vary depending upon the characteristics of the leaves. Typically, however, complete shielding can occur before a dropped needle has fallen one foot.